A long term evolution (LTE) system requires time alignment of uplink signals coming from different UEs to an evolved NodeB (eNB), so as to ensure orthogonality of the uplink signals between UEs and help eliminate intra-cell interference. Time alignment of uplink transmission is implemented by performing timing advance (TA) at a UE side.
Currently, a UE first sends a physical random access channel (PRACH) preamble sequence in uplink during initial access to an LTE network. After measuring the preamble sequence, an eNB returns a TA command to the UE by using a random access response (RAR) message. The UE performs corresponding uplink time alignment according to the TA command in the received RAR message. An amount of the time alignment is given by NTA=TA×16Ts, where TA is the value or the index value of the TA command, and Ts=1/(15000*2048)s=0.52 μs. The value of the TA command returned to the UE from the eNB ranges from 0 to 1282, and accordingly, the value of TA ranges from 0 ms to 0.67 ms, which is capable of supporting only comparatively small coverage.